Light-emitting device and light-emitting system

ABSTRACT

A light-emitting unit ( 140 ) is formed on a substrate ( 100 ), and includes a light-transmitting first electrode ( 110 ), a light-reflective second electrode ( 130 ), and an organic layer ( 120 ) located between the first electrode ( 110 ) and the second electrode ( 130 ). A light-transmitting region is located between a plurality of light-emitting units ( 140 ). An insulating film ( 150 ) defines an end ( 142 ) of the light-emitting unit ( 140 ). A sealing member ( 200 ) is fixed to the light-emitting unit ( 140 ) directly or through an adhesive layer ( 210 ). In addition, a thickness of the substrate ( 100 ) is d, and a width of a portion of the second electrode ( 130 ) that is further on the outer side of the light-emitting unit ( 140 ) than the end ( 142 ) is W, d/2≤W is established.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage entry of PCT Application No:PCT/JP2016/056833 filed Mar. 4, 2016, the contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a light-emitting device and alight-emitting system.

BACKGROUND ART

In recent years, there has been progress in the development oflight-emitting devices using organic EL. Such light-emitting devices areused as illumination devices or display devices and configured of anorganic layer interposed between a first electrode and a secondelectrode. Generally, a transparent material is used for the firstelectrode, and a metal material is used for the second electrode.

One of the light-emitting devices which utilizes the organic EL is atechnology described in Patent Document 1. In order to provide a displaydevice using organic EL with optical transparency (or a “see-through”property), the technology in Patent Document 1 provides secondelectrodes only in a portion of a pixel. In such a configuration, sincea region located between a plurality of second electrodes transmitslight, the display device is capable of having optical transparency.Meanwhile, in the technology described in Patent Document 1, alight-transmitting insulating film is formed between the plurality ofsecond electrodes to define the pixel. In Patent Document 1, aninorganic material such as silicon oxide and a resin material such asacrylic resin are exemplified as materials of the insulating film.

RELATED ART DOCUMENT Patent Document

[Patent Document 1]: Japanese Unexamined Patent Application PublicationNo. 2011-23336

SUMMARY OF THE INVENTION

In a light-emitting device of a light-transmitting type in which lightis desired to be extracted only from one surface (a front surface),there is a case where a portion of the light leaks out also from asurface of the opposite side (a rear surface). In this case, visuallyrecognizing the opposite side from the rear surface side through thelight-emitting device may become difficult, and a light extractionefficiency on the front surface may decrease.

An example of the problem to be solved by the present invention is toreduce a leakage of light from a surface opposite to a light-emittingsurface in a light-transmitting-type light-emitting device.

Means for Solving the Problem

The invention described in claim 1 is a light-emitting device including:

a light-transmitting substrate;

a plurality of light-emitting units formed on the substrate, eachlight-emitting unit including a light-transmitting first electrode, alight-reflective second electrode, and an organic layer located betweenthe first electrode and the second electrode;

a light-transmitting region located between the plurality oflight-emitting units; and

an insulating film that defines an end of the light-emitting unit,

in which a sealing member is fixed to the light-emitting unit directlyor through an adhesive layer, and

in which when the thickness of the substrate is d and the width of aportion of second electrode which is located further on the outer sideof the light-emitting unit than the end is W, d/2≤W is established.

The invention described in claim 9 is a light-emitting system including:

a partition member that partitions a space from an exterior;

a light-transmitting substrate disposed on the partition member;

a plurality of light-emitting units formed on one surface of thesubstrate, each light-emitting unit including a light-transmitting firstelectrode, a light-reflective second electrode, and an organic layerlocated between the first electrode and the second electrode;

a light-transmitting region located between the plurality oflight-emitting units;

an insulating film that defines an end of the light-emitting unit; and

a covering film that directly covers the light-emitting unit, theinsulating film, and the substrate in the light-transmitting region,

in which when the thickness of the substrate is d and the width of aportion of the second electrode which is located further on the outerside of the light-emitting unit than the end is W, d/2≤W is established.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects described above, and other objects, features and advantagesare further made apparent by a suitable embodiment that will bedescribed below and the following accompanying drawings.

FIG. 1 is a cross-sectional view of a configuration example of alight-emitting device according to an embodiment.

FIG. 2 is an enlarged view of a light-emitting unit in a light-emittingdevice.

FIG. 3 is a cross-sectional view of another configuration example of alight-emitting device according to an embodiment.

FIG. 4 is a plan view of a light-emitting device.

FIG. 5 is an enlarged view of a region of FIG. 1 surrounded by a dottedline α.

FIG. 6 is a view of an example of a light path in a substrate of lightemitted from a light-emitting unit.

FIG. 7 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 1.

FIG. 8 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 2.

FIG. 9 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 3.

FIG. 10 is a cross-sectional view of another configuration example of alight-emitting system according to Modification Example 3.

FIG. 11 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 4.

FIG. 12 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 5.

FIG. 13 is a diagram of a measured result of a relationship betweenobservation angles and intensities of light leaked to the rear surfacein a light-emitting device according to an example and a comparativeexample.

DESCRIPTION OF EMBODIMENT

An embodiment of the present invention will be described below byreferring to the drawings. Moreover, in all the drawings, the sameconstituent elements are given the same reference numerals, anddescriptions thereof will not be repeated.

FIG. 1 is a cross-sectional view showing a configuration example of alight-emitting device 10 according to an embodiment. A person P isviewing a light-emitting surface of the light-emitting device 10 from adirection perpendicular to a substrate 100 in FIG. 1. FIG. 2 is anenlarged view of a light-emitting unit 140 in the light-emitting device10. The light-emitting device 10 according to the embodiment is alighting device or a display device. FIG. 1 and FIG. 2 show a case wherethe light-emitting device 10 is a lighting device.

The light-emitting device 10 includes a light-transmitting substrate100, a plurality of light-emitting units 140, a light-transmittingregion, and an insulating film 150. The light-emitting units 140 areformed on the substrate 100, each light-emitting unit 140 including alight-transmitting first electrode 110, a light-reflective secondelectrode 130, and an organic layer 120 located between the firstelectrode 110 and the second electrode 130. The light-transmittingregion is located between the plurality of light-emitting units 140. Theinsulating film 150 defines an end 142 of the light-emitting unit 140.The sealing member 200 is fixed to the light-emitting unit 140 directlyor with an adhesive layer 200 interposed therebetween. Further, when thethickness of the substrate 100 is d and the width of a portion of thesecond electrode 130 which is further on the outer side of thelight-emitting unit 140 than the end 142 is W, d/2≤W is established. Adetailed description will be provided below.

Meanwhile, in the descriptions below, based on the light-emitting unit140, a side on which the substrate 100 is provided is called a frontsurface of the light-emitting device 10, and a side on which the sealingmember 200 is provided is called a rear surface of the light-emittingdevice 10.

In the present embodiment, the light-emitting device 10 is a lightingdevice, and includes the substrate 100, the plurality of light-emittingunits 140, and the insulating layer 150. A light-transmitting materialis used for the substrate 100. The plurality of the light-emitting units140 are separated from each other, each including the first electrode110, the organic layer 120, and the second electrode 130. The firstelectrode 110 is a light-transmitting electrode, and the secondelectrode 130 has light shielding properties or light reflectivity. Thefirst electrode 110 and the second electrode 130 are at least partiallyoverlapped. However, a portion of a region in which the second electrode130 is formed may also be a light-transmitting electrode. The organiclayer 120 is located between the first electrode 110 and the secondelectrode 130. The insulating layer 150 covers an edge of the firstelectrode 110. Moreover, at least a portion of the insulating layer 150is not covered by the second electrode 130. Meanwhile, the secondelectrode 130 may cover the entirety of the insulating film 150.

Further, when viewed in a direction perpendicular to the substrate 100,the light-emitting device 10 includes a first region 102, a secondregion 104, and a third region 106 (a light-transmitting region). Thefirst region 102 overlaps the second electrode 130. That is, when viewedin the direction perpendicular to the substrate 100, the first region102 is a region which is covered by the second electrode 130. In a casewhere the second electrode 130 includes reflectivity, the first region102 does not transmit light either from a front surface to a rearsurface or from the rear surface to the front surface of thelight-emitting device 10 or the substrate 100. The second region 104 isnot covered by the second electrode 130 but overlaps the insulating film150. The third region 106 is neither covered by the second electrode 130nor overlapped by the insulating film 150, and is light-transmitting. Inaddition, since the width of the second region 104 is narrower than thatof the third region 106, the light-emitting device 10 has sufficientoptical transparency. Meanwhile, the second region 104 and the thirdregion 106 may form the light-transmitting region.

The substrate 100 is polygonal, for example, rectangular, or round. In acase where the substrate 100 is a resin substrate, the substrate 100 isformed using, for example, polyethylene naphthalate (PEN), polyethersulphone (PES), polyethylene terephthalate (PET), or polyimide. Arefractive index n of the substrate 100 is not particularly limited, butis, for example, equal to or greater than 1.5. In addition, in a casewhere the substrate 100 is a resin substrate, an inorganic barrier filmof SiN_(x), SiON, or the like is preferably formed on at least onesurface (preferably, both surfaces) of the substrate 100 in order toprevent moisture from permeating the substrate 100. Further, an opticalfilm such as an antireflective film may be provided on at least onesurface of the substrate 100. In this case, as described later, athickness including the inorganic barrier film and the optical film maybe defined as the thickness d of the substrate 100.

The light-emitting unit 140 is formed on one surface of the substrate100. The light-emitting unit 140 has a configuration in which the firstelectrode 110, the organic layer 120, and the second electrode 130 arelaminated in this order. In a case where the light-emitting device 10 isa lighting device, the plurality of light-emitting units 140 arelinearly extended. On the other hand, in a case where the light-emittingdevice 10 is a display device, the plurality of light-emitting units 140may be disposed to constitute a matrix or may be disposed to constitutesegments or to display a predetermined shape (for example, an icon).Further, the plurality of light-emitting units 140 are formed inaccordance with each pixel.

The first electrode 110 is a transparent electrode having opticaltransparency. A material of the transparent electrode contains a metal,for example, a metal oxide such as an indium tin oxide (ITO), an indiumzinc oxide (IZO), an indium tungsten zinc oxide (IWZO), a zinc oxide(ZnO), or the like. The thickness of the first electrode 110 is, forexample, equal to or greater than 10 nm and equal to or less than 500nm. The first electrode 110 is formed by, for example, sputtering orvapor deposition. Meanwhile, the first electrode 110 may be a conductiveorganic material such as carbon nanotubes or PEDOT/PSS. In the drawing,a plurality of the first electrodes 110 are linearly formed in parallelto each other on the substrate 100. Therefore, the first electrode 110is located neither in the second region 104 nor in the third region 106.Meanwhile, since the first electrode 110 is a transparent electrodehaving optical transparency, it may be located in the second region 104and the third region 106.

Further, an auxiliary electrode (not shown in the drawing) may beprovided in the first electrode 110. In this case, the auxiliaryelectrode is formed of a material having a lower resistance value thanthat of the first electrode 110 and in contact with the first electrode110. The auxiliary electrode is formed using, for example, at least onemetal layer. In addition, the auxiliary electrode is covered by theinsulating film 150. Therefore, the auxiliary electrode is not directlyconnected to any of the organic layer 120 and the second electrode 130.The auxiliary electrode is provided, thereby lowering the apparentresistance value of the first electrode 110.

The organic layer 120 includes a light-emitting layer. The organic layer120 has a configuration in which, for example, a hole injection layer, alight-emitting layer, and an electron injection layer are laminated inthis order. A hole transport layer may be formed between the holeinjection layer and the light-emitting layer. In addition, an electrontransport layer may be formed between the light-emitting layer and theelectron injection layer. The organic layer 120 may be formed usingvapor deposition. In addition, at least one layer of the organic layer120, for example, a layer which is in contact with the first electrode110, may be formed using a coating method such as ink jetting, printing,or spraying. Meanwhile, in this case, the remaining layers of theorganic layer 120 are formed using vapor deposition. In addition, alllayers of the organic layer 120 may be formed using a coating method.

The second electrode 130 includes a metal layer constituted of a metalselected from a first group consisting of, for example, Al, Au, Ag, Pt,Mg, Sn, Zn, and In, or an alloy of metals selected from the first group.In this case, the second electrode 130 has light shielding properties.The thickness of the second electrode 130 is, for example, equal to orgreater than 10 nm and equal to or less than 500 nm. However, the secondelectrode 130 may be formed using a material exemplified as the materialof the first electrode 110. The second electrode 130 is formed using,for example, sputtering or vapor deposition. In the example shown in thedrawing, the light-emitting device 10 includes a plurality of linearsecond electrodes 130. Each second electrode 130 is provided for eachfirst electrode 110, and the width of each second electrode 130 is widerthan that of each first electrode 110. Therefore, when viewed from adirection perpendicular to the substrate 100, the entire first electrode110 is overlapped and covered by the second electrode 130 in the widthdirection. In addition, the width of the first electrode 110 may bewider than that of the second electrode 130, and when viewed from adirection perpendicular to the substrate 100, the second electrode 130may be entirely covered by the first electrode 110 in the widthdirection. Further, the second electrode 130 may cover the entirety ofthe insulating film 150, and the second electrode 130 may be provided tospread to a region in which neither the first electrode 110 nor theinsulating layer 150 are formed.

The edge of the first electrode 110 is covered by the insulating layer150. The insulating layer 150 is formed of a photosensitive resinmaterial such as, for example, polyimide, and surrounds a portion of thefirst electrode 110, the portion serving as the light-emitting unit 140.An edge of the second electrode 130 in the width direction is locatedover the insulating film 150. In other words, when viewed from adirection perpendicular to the substrate 100, a portion of theinsulating layer 150 protrudes from the second electrode 130. Inaddition, in the example illustrated in the drawing, the organic layer120 is formed on top and side of the insulating layer 150. However, theorganic layer 120 is divided in a region between the light-emittingunits 140 next to each other. Further, in a case where the organic layer120 has light-transmitting properties, the organic layer 120 need not bedivided between the light-emitting units 140 next to each other.

As described above, the light-emitting device 10 includes the firstregion 102, the second region 104, and the third region 106. The firstregion 102 overlaps the second electrode 130. The second region 104 is aregion which is not covered by the second electrode 130 but overlaps theinsulating film 150. In the example illustrated in the drawing, theorganic layer 120 is also formed in the second region 104. The thirdregion 106 is a region which is not covered by the second electrode 130and does not overlap with the second electrode 130. In the example shownin the drawing, the organic layer 120 is not formed in at least aportion of the third region 106. In addition, the width of the secondregion 104 is narrower than that of the third region 106. Moreover, thewidth of the third region 106 may be wider or narrower than that of thefirst region 102. In a case where the width of the first region 102 is1, the width of the second region 104 is, for example, equal to orgreater than 0 (or more than 0) and equal to or less than 0.2, and thewidth of the third region 106 is, for example, equal to or greater than0.3 and equal to or less than 2. In addition, the width of the firstregion 102 is, for example, equal to or greater than 50 μm and equal toor less than 500 μm, and the width of the second region 104 is, forexample, equal to or greater than 0 μm (or more than 0 μm) and equal toor less than 100 μm, and the width of the third region 106 is, forexample, equal to or greater than 15 μm and equal to or less than 1,000μm.

Further, the light-emitting device 10 may be provided with a coveringfilm which directly covers the light-emitting unit 140, the insulatingfilm 150, and the substrate 100 in the light-transmitting region. Thecovering film is, for example, the adhesive layer 210 or alater-described sealing member.

The sealing member 200 covers the light-emitting unit 140 and theinsulating film 150, and is fixed to the light-emitting unit 140directly or through an adhesive layer. A space (a layer made of amaterial other than a solid) is not interposed between thelight-emitting unit 140 and the sealing member 200. The sealing member200 and the adhesive layer 210 have light-transmitting properties. Thepresent drawing shows an example of the sealing member 200 being fixedthrough the adhesive layer 210 to the light-emitting unit 140. When thesealing member 200 is fixed through the adhesive layer 210 to thelight-emitting unit 140, the sealing member 200 is formed by, forexample, glass, or a light-transmitting thin plate (or foil) such as abarrier film. In addition, the edge of the sealing member 200 is fixedusing an adhesive or the like to the substrate 100. Thereby, a space forhousing the light-emitting unit 140 is formed between the sealing member200 and the substrate 100. Further, this space is filled by an adhesivesuch as an epoxy. In this case, the adhesive layer 210 is configured bythe adhesive. In the example in the drawing, the second electrode 130 isin contact with the adhesive layer 210, and in addition, is in contactwith the sealing member 200.

On the other hand, in a case where the sealing member 200 is directlyfixed to the light-emitting unit 140, the sealing member 200 is formedby directly sealing over the substrate 100 by, for example, resin. Inaddition, the sealing member 200 is in contact with the second electrode130. In this case, the thickness of the sealing member 200 is notparticularly limited, however, for example, is equal to or greater than20 μm and equal to or less than 300 μm.

FIG. 3 is a cross-sectional view of another configuration example of thelight-emitting device 10. The present drawing corresponds to theabove-mentioned FIG. 1. In the example shown in the drawing, a sealingfilm 190 is formed between the light-emitting unit 140 and the adhesivelayer 210 as a covering film. In addition, a barrier film 160 isadditionally formed between the substrate 100 and the first electrode110, between the light-emitting unit 140 and the sealing member 200, andon the side of the sealing member 200 opposite to the light-emittingunit 140. Further, the light-emitting unit 140 is covered by the sealingfilm 190 and the barrier film 160. In the example shown in the drawing,the sealing member 200 is fixed to the light-emitting unit 140 with thebarrier film 160, the sealing film 190, and the adhesive layer 210interposed therebetween.

The sealing film 190 is formed on the surface of the substrate 100 onwhich at least the light-emitting unit 140 is formed to cover thelight-emitting unit 140. In the example shown in the drawing, thesealing film 190 is in contact with the second electrode 130. Thesealing film 190 is formed by, for example, an insulating material, morespecifically, an inorganic material such as an aluminum oxide or antitanium oxide. Further, the thickness of the sealing film 190 ispreferably equal to or less than 300 nm. In addition, the thickness ofthe sealing film 190 is, for example, equal to or greater than 50 nm.

The sealing film 190 is formed by, for example, ALD (Atomic LayerDeposition). In this case, high step coverage of the sealing film 190 isobtained. Further in this case, the sealing film 190 may have amultilayer structure in which plural layers are laminated. In this case,the sealing film 190 may be configured by repeatedly laminating a firstsealing layer composed of a first material (for example, aluminumoxide), and a second sealing layer composed of a second material (forexample, titanium oxide). The lowermost layer may be any of the firstsealing layer and the second sealing layer. The uppermost layer may alsobe any of the first sealing layer and the second sealing layer. Inaddition, the inorganic film 190 may be a single layer in which thefirst material and the second material are mixed.

However, the sealing film 190 may be formed using another film formationmethod, for example, CVD or sputtering. In this case, the sealing film190 is formed of an insulating film such as SiO₂ or SiN or the like, andthe thickness thereof is, for example, equal to or greater than 10 nmand equal to or less than 1,000 nm.

The barrier film 160 is formed by, for example, ALD, CVD, or sputtering.The barrier film 160 is formed of an insulating film such as Al₂O₃,SiO₂, SiN, and Si₃N₄, and the thickness thereof is, for example, equalto or greater than 50 nm and equal to or less than 5,000 nm. Further,the barrier film 160 may have a multilayer structure in which multiplelayers are laminated. The multilayer structure may include, for example,an organic planarization layer.

Meanwhile, in the example shown in the drawing, one or more of aplurality of barrier films 160 and the sealing film 190 may be omitted.Further, in a case where the sealing member 200 is formed on the sealingfilm 190 in contact therewith, the sealing film 190 together with thesealing member 200 may be considered as a sealing member. In this case,it can be said that the sealing member is directly fixed on thelight-emitting unit 140.

FIG. 4 is a plan view of the light-emitting device 10. Meanwhile, FIG. 1corresponds to a cross-section taken along line A-A of FIG. 4. In theexample shown in the drawing, the plurality of the light-emitting units140 extend in the same direction as each other when viewed from adirection perpendicular to the substrate 100. Further, each of the firstregion 102, the second region 104, and the third region 106 extendslinearly and in the same direction as each other. In addition, as shownin the drawing and FIG. 1, the second region 104, the first region 102,the second region 104, and the third region 106 are repeatedly alignedin this order. Meanwhile, the direction perpendicular to the substrate100 is a direction perpendicular to the main surface of the substrate100.

FIG. 5 is an enlarged view of a region of FIG. 1 surrounded by a dottedline α. A rear surface 109 of the substrate 100 is a surface on the sidefacing the second region 104, and a front surface 108 of the substrate100 is a surface on the opposite side to the side facing the secondregion 104. An arrow L₁ in the drawing shows an example of a light pathwhich is taken by light emitted from the light-emitting unit 140advancing toward the front surface 108 of the substrate 100. Further, anarrow L₂ shows a route of light which is refracted and emitted to theoutside of the light-emitting device 10 out of the light which hasreached the front surface 108 of the substrate 100. In addition, adotted arrow L₃ shows a route of light which is reflected on aninterface of air and the substrate 100 and advances to the rear surfaceside of the light-emitting device 10.

Here, when the refractive index of the substrate 100 is n, in a casewhere an incident angle is greater than a critical angle θ_(c), light istotally reflected. Meanwhile, when the refractive index of the substrate100 is n, the critical angle θ_(c)=arcsin(1/n) is established. Suchtotally-reflected light is emitted from the end without being extractedfrom either the front surface or the rear surface when the surface ofthe substrate 100 is flat and light is not scattered. Therefore, thelight will not leak from the rear surface. On the other hand, a portionof light having an incident angle which is smaller than the criticalangle θ_(c) is extracted as emitted light, and another portion isregularly reflected at the same angle. When this regularly reflectedlight L₃ reaches the sealing member 200 or the adhesive layer 210, aportion thereof is emitted to the outside of the light-emitting device10 and then leaks from the rear surface.

When light becomes incident on the surface of the substrate 100 from thefront, that is, when an incident angle θ is 0 degrees, a ratio R of anintensity of regular reflection to an intensity of incident light isR=((n−1)/(n+1))² by Snell's law. For example, when the substrate 100 isglass having a refractive index of n=1.5, the ratio R is approximately4%. This ratio R becomes greater as the incident angle θ becomes largerin accordance with Fresnel's law. Thus, even when the ratio R of theregular reflection is several percent, an influence to light leaked fromthe rear surface must be considered. This is because the regularreflection on the rear surface 109 is also only several percent and agreater portion of the regularly reflected light on the front surface108 directly becomes light leaked from the rear surface.

In the light-emitting device 10 according to the present embodiment, asdescribed above, a relationship of d/2≤W is established between thethickness d of the substrate 100 and the width W of a portion of thesecond electrode 130 on the further on the outer side of thelight-emitting unit 140 than the end 142 (hereinafter called “theoverlapping region”). Therefore, approximately equal to or more than 30%of the regularly reflected light on the front surface 108 is reflectedagain in the overlapping region to the front surface 108 side, and it ispossible to reduce the light leaked from the rear surface.

Here, W is the width of a portion of the second electrode 130 which isfurther on the outer side of the light-emitting unit 140 than the end142 in a cross section (which corresponds to a cross-section taken alongline A-A in FIG. 4) which is perpendicular to both the surface of thesubstrate 100 and an extending direction of the light-emitting unit 140.In addition, it can also be said that the width W is the shortestdistance between an end of the light-emitting unit 140 and an end of thesecond electrode 130. Meanwhile, the thickness d of the substrate 100may be defined as a distance between a surface of the first electrode110 facing the substrate 100 and a surface of the substrate 100 or asurface of the substrate 100 and a layer laminated thereon exposed to agas phase. That is, in a case where a barrier layer, the optical film,or the like is laminated on at least one surface of the substrate 100,the thickness including the barrier layer or the optical film can beconsidered as the thickness d.

In addition, in the light-emitting device 10, it is more preferable thatd×tan(arcsin(1/n))≤W<3d×tan(arcsin (1/n)) is satisfied.

FIG. 6 is a diagram of an example of the light path in the substrate100, of the light emitted from the light-emitting unit 140. In thediagram, the light-emitting unit 140 is illustrated in a simplified way.Further, in the present drawing, a dotted arrow shows the light path oflight which is totally reflected on the interface of the substrate 100and air. In addition, a length shown as W₁ in the drawing isd×tan(arcsin(1/n)). That is, W₁=d×tan θ_(c) is established, and sincethe critical angle is θ_(c)=arcsin(1/n), W₁=d×tan(arcsin(1/n)) isestablished. Meanwhile, it can be said that W₁ is a distance which isadvanced by light incident on the interface between the substrate 100and the air at the critical angle in an in-plane direction of thesubstrate 100 from the rear surface 109 to the front surface 108 throughthe substrate 100. Further, as shown in the diagram, light from thelight-emitting unit 140 reaches within the range of a distance of 2×W₁from the end of the light-emitting unit 140, that is, a distance of2d×tan(arcsin(1/n)). Thus, by establishing d×tan(arcsin(1/n))≤W,approximately equal to or more than 50% of the regularly reflected lightis reflected again in the overlapping region to the front surface 108side, and thus it is possible to further reduce the light leaked fromthe rear surface. Meanwhile, by establishing W<3d×tan(arcsin(1/n)),optical transparency of the light-emitting device 10 is prevented frombecoming impaired. Meanwhile, here, the thickness of the first electrode110 or the thickness of the insulating film 150 is sufficiently smallwith respect to the thickness d of the substrate 100 and can be ignored.

In the light-emitting device 10, it is more preferable that2d×tan(arcsin(1/n))≤W<3d×tan(arcsin(1/n)) is satisfied. When the aboveis satisfied, almost all of the regularly reflected light having anangle smaller than the critical angle is reflected again in theoverlapping region to the front surface 108 side, and it is possible tostill further reduce light leaked from the rear surface. Meanwhile, theoptical transparency of the light-emitting device 10 is prevented frombecoming impaired.

Meanwhile, in a case where one or more layers of a barrier layer and thelike are laminated on at least one surface of the substrate 100, thelayer(s) and the substrate may be considered together as a substratecomposed of a plurality of layers. In this case, the refractive index ofthe thickest layer of the plurality of layers can be set as therefractive index n of the substrate. Further, a mean value of theplurality of layers may also be set as the refractive index n of thesubstrate. At least in one of the case where the refractive index of thethickest layer of the plurality of layers is set as the refractive indexn, and the case where the mean value of the plurality of layers is setas n, it is more preferable thatd×tan(arcsin(1/n))≤W<3d×tan(arcsin(1/n)) is satisfied, and it is evenmore preferable that 2d×tan(arcsin(1/n))≤W<3d×tan(arcsin(1/n)) issatisfied.

Meanwhile, in FIG. 1 and FIG. 2, an example was shown in which thewidths W of the overlapping regions located on the right and the leftwith respect to one light-emitting unit 140 are the same. However, atleast apart of the widths W of the plurality of overlapping regions withrespect to one light-emitting unit 140 may be different in size. Inaddition, in FIG. 1 and FIG. 2, an example is illustrated of a casewhere all of the widths W of the overlapping regions with respect to theplurality of the light-emitting units 140 are the same, but at least apart of the widths W of the overlapping regions of the plurality of thelight-emitting units 140 may be different in size. In a case where thereare plurality of overlapping regions having widths W in different sizes,it is sufficient if the largest width W satisfies d/2≤W. In addition, itis more preferable that the smallest width W satisfies a relationship ofd/2≤W.

The substrate 100 is a substrate, such as, for example, a glasssubstrate or a resin substrate which has optical transparency. Thesubstrate 100 may have flexibility. In a case where the substrate hasflexibility, the thickness d of the substrate 100 is, not particularlylimited, but, for example, equal to or greater than 10 μm and equal toor less than 1,000 μm. Particularly, the thickness d of the substrate100 is preferably equal to or less than 100 μm. When the thickness d ofthe substrate 100 is equal to or less than 100 μm, even in a case whered/2≤W is satisfied, the overlapping region does not become too large,and thereby it is possible to secure satisfactory optical transparencyof the light-emitting device 10.

Next, a method of manufacturing the light-emitting device 10 will bedescribed. First, the first electrode 110 is formed on the substrate 100by, for example, sputtering. Then, the first electrode 110 is formed ina predetermined pattern by, for example, photolithography. Meanwhile,before forming the first electrode 110, the inorganic barrier film maybe formed on the surface of the substrate 100 by sputtering or the like.

The insulating layer 150 is then formed over an edge of the firstelectrode 110. For example, in a case where the insulating layer 150 isformed of a photosensitive resin, the insulating layer 150 is formed ina predetermined pattern by undergoing exposure and development steps.Next, the organic layer 120 and the second electrode 130 are formed inthis order. In a case where the organic layer 120 includes a layerformed by vapor deposition, this layer is formed in a predeterminedpattern using a mask or the like. The second electrode 130 is alsoformed in a predetermined pattern using, for example, a mask.Thereafter, the light-emitting unit 140 is sealed using the sealingmember 200.

According to the embodiment, d/2≤W is established between the thicknessd of the substrate 100 and the width W of a portion of the secondelectrode 130 which is located further on the outer side of thelight-emitting unit 140 than the end 142. Therefore, it is possible toreduce the light leaked from the rear surface by further reflectingreflected light from the surface of the substrate 100 on the secondelectrode 130 to the substrate 100 side.

Modification Example 1

FIG. 7 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 1. Thislight-emitting system includes the afore-mentioned light-emitting device10 and a partition member 20. Specifically, the light-emitting systemincludes a light-transmitting partition member 20, a light-transmittingsubstrate 100, a plurality of light-emitting units 140, alight-transmitting region, an insulating film 150, and a covering film.The partition member 20 partitions a space from the outside. Thesubstrate 100 is disposed on the partition member 20. The light-emittingunit 140 is formed on one surface of the substrate 100. Further, thelight-emitting unit 140 includes a light-transmitting first electrode110, a light-reflective second electrode 130, and an organic layer 120located between the first electrode 110 and the second electrode 120.The light-transmitting region is located between the plurality oflight-emitting units 140. The insulating film 150 defines an end 142 ofthe light-emitting unit 140. The covering film directly covers thelight-emitting unit 140, the insulating film 150, and the substrate 100in the light-transmitting region. In addition, when the thickness of thesubstrate 100 is d and the width of a portion of the second electrode130 which is further on the outer side of the light-emitting unit 140than the end 142 is W, d/2≤W is established. A detailed description willbe provided below.

The partition member 20 has optical transparency and partitions a spacefrom the exterior thereof. This space is, for example, a space occupiedby a person, or a space having an object such as a commercial productdisposed therein. The light-emitting device 10 includes the sameconfiguration as that of the above-mentioned embodiment. In the exampleshown in the drawing, a surface of the substrate 100 on the sideprovided with the light-emitting unit 140 (a first surface 100 a) isdirected toward the space occupied by a person.

The partition member 20 is, for example, a window of a mobile object 30for transporting a person, or a window of a showcase, and is formedusing glass or a light-transmitting resin. The mobile object 30 is, forexample, an automobile, a train, or an airplane. In a case where themobile object 30 is an automobile, the partition member 20 is awindshield, a rear windshield, or a side window (for example, a doorwindow) installed at the side of a seat. In a case where the partitionmember 20 is a rear windshield, the plurality of light-emitting units140 function as, for example, a brake light. In addition, in a casewhere the partition member 20 is a windshield or a rear windshield, theplurality of light-emitting units 140 may be a turn signal light. Inaddition, the partition member 20 may be a window for partitioning theinterior and the exterior of a room such as a meeting room. Thelight-emitting system may allow to distinguish whether the meeting roomis occupied, depending on the lighting/non-lighting of thelight-emitting units 140.

Further, a second surface 100 b of the light-emitting device 10 is fixedto the inner surface (a first surface 22) of the partition member 20through an adhesive layer 300. Here, the second surface 100 b is asurface on the opposite side of the first surface 100 a, and a surfaceon a light extraction side. Therefore, light emitted from thelight-emitting unit 140 of the light-emitting device 10 is emitted tothe exterior of the above-mentioned space (for example, the mobileobject 30) through the partition member 20. Further, the light-emittingdevice 10 has optical transparency. Therefore, a person can view theexterior and the interior of the space through the partition member 20.For example, a person located inside the mobile object 30 can visuallyrecognize the outside of the mobile object 30 through the partitionmember 20.

The adhesive layer 300 fixes the light-emitting device 10 to thepartition member 20. Insofar as a material fulfilling such a function isused, there is no particular limitation to the material of the adhesivelayer 300. In the present modification example, a portion (for example,two sides facing each other) of the second surface 100 b of thesubstrate 100 is fixed to the first surface 22 of the partition member20 with the adhesive layer 300 interposed therebetween. Therefore, anair gap is formed between the substrate 100 and the first surface 22.Even in such a case, d/2≤W is established in the light-emitting device10 between the thickness d of the substrate 100 and the width W in theoverlapping region, thereby further reflecting reflected light from asurface of the substrate 100 on the second electrode 130 to a side ofthe substrate 100. Thus, it is possible to reduce light leaked from therear surface.

Modification Example 2

FIG. 8 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 2. Thelight-emitting system according to the present modification example hasthe same configuration as that of the light-emitting system according toModification Example 1, except that a light-emitting device 10 ismounted on the partition member 20 on an outer surface (a second surface24) of the mobile object 30.

The light-emitting device 10 according to the present modificationexample has the same configuration as that of the above-mentionedembodiment. However, in the light-emitting device 10, a surface thereofon the opposite side of the partition member 20 serves as a lightextraction surface. In order to achieve such a configuration, a surfaceof the light-emitting device 10 on a first surface 100 a side may bemade to face the partition member 20.

In the present modification example also, the same as the embodiment, itis possible to reduce light leaked from a rear surface.

In addition, light emitted from the light-emitting device 10 is emitteddirectly to the exterior of the mobile object 30 without passing throughthe partition member 20. Therefore, compared to

Modification Example 1, a person who is outside the mobile object 30 caneasily recognize the light from the light-emitting device 10. Inaddition, since the light-emitting device 10 is installed on theexterior of the mobile object 30, that is, on the partition member 20 onthe second surface 24 side, it is possible to prevent the emitted lightfrom the light-emitting device 10 from being reflected on the partitionmember 20 and entering the interior of the mobile object 30.

Modification Example 3

FIG. 9 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 3. Thelight-emitting system according to the present modification example hasthe same configuration as that of the light-emitting system according toModification Example 1, except that the light-emitting device 10 isfixed to a partition member 20 using fixing members 310.

The fixing member 310 is a frame-like member with a lower surfacethereof fixed to the partition member 20 using an adhesive layer 300. Anupper portion of the fixing member 310 is bent toward the insidethereof, and this bent portion holds an edge of the light-emittingdevice 10. However, the shape of the fixing member 310 is not limited tothe example shown in the drawing.

In the present modification example, a convex portion 101 is provided ona second surface 100 b of the light-emitting device 10 to surround alight-emitting unit 140 when viewed from a direction perpendicular tothe substrate 100. Therefore, an air gap is formed between the substrate100 and a first surface 22 in a region overlapped with thelight-emitting unit 140 when viewed from a direction perpendicular tothe substrate. The convex portion 101 is formed, for example, of a resinmaterial. Even in such a case, d/2≤W is established in thelight-emitting device 10 between the thickness d of the substrate 100and the width W of an overlapping region, thereby further reflectingreflected light from a surface of the substrate 100 on the secondelectrode 130 to a side of the substrate 100. Thus, it is possible toreduce light leaked from the rear surface.

FIG. 10 is a cross-sectional view of another configuration example of alight-emitting system according to Modification Example 3. Asillustrated in the present drawing, there is a case where the partitionmember 20 is curved in a direction projecting to the outside of themobile object 30. In such a case, it is difficult to directly fix theflat plate-like light-emitting device 10 on the inner surface (the firstsurface 22) of the partition member 20. However, when the fixing member310 is used, even in such a case, the light-emitting device 10 can befixed on the first surface 22. Meanwhile, the convex portion 101illustrated in FIG. 9 may or may not be provided on the substrate 100.

In a case where a curved partition member 20 and the flat plate-likelight-emitting device 10 are fixed by the above method, an air gap isformed between the substrate 100 and the first surface 22. Even in sucha case, d/2≤W is established in the light-emitting device 10 between thethickness d of the substrate 100 and the width W in an overlappingregion, thereby further reflecting reflected light from the surface ofthe substrate 100 on the second electrode 130 to the side of thesubstrate 100. Thus, it is possible to reduce the light leaked from therear surface.

Modification Example 4

FIG. 11 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 4. Thelight-emitting system according to the present modification example hasthe same configuration as that of the light-emitting system according tothe modification examples 1 to 3, except that a plurality oflight-emitting devices 10 are installed on the partition member 20.Meanwhile, in FIG. 11, the example corresponding to FIG. 9 isillustrated in a simplified way. Turning on and off of the lights of theplurality of light-emitting devices 10 may be controlled in accordancewith control signals that are the same or different from each other.

According to the present modification example, the same as theembodiment, it is possible to reduce light leaked from a rear surface.

Modification Example 5

FIG. 12 is a cross-sectional view of a configuration example of alight-emitting system according to Modification Example 5. Thelight-emitting system according to the present modification example hasthe same configuration as that of the light-emitting system according toModification Example 1, except for the configuration of the partitionmember 20 and the position of the light-emitting device 10.

In the present modification example, the partition member 20 has aconfiguration in which a plurality of light-transmitting members 21 (forexample, glass plates or resin plates) overlap each other. Further, thelight-emitting device 10 is installed on the partition member 20 bybeing interposed between the light-transmitting members 21 next to eachother.

In the present modification example, a convex portion 101 is provided onthe second surface 100 b of the light-emitting device 10 to surround thelight-emitting unit 140 when viewed from a direction perpendicular tothe substrate 100. Therefore, an air gap is formed between the substrate100 and a surface 211 of the light-transmitting member 21 which facesthe substrate 100 in a region overlapped with the light-emitting unit140 when viewed from a direction perpendicular to the substrate. Even insuch a case, d/2≤W is established in the light-emitting device 10between the thickness d of the substrate 100 and the width W in anoverlapping region, thereby further reflecting reflected light from asurface of the substrate 100 on the second electrode 130 to a side ofthe substrate 100. Thus, it is possible to reduce light leaked from arear surface.

Example

A light-emitting device was manufactured as illustrated in FIG. 3 asfollows. Specifically, first, a polyimide sheet provided with a barrierfilm was prepared as a substrate. Here, a refractive index of thepolyimide sheet was 1.6, and the thickness of the substrate includingthe barrier film was 20 μm. Next, a light-emitting unit was formed onthe substrate. The width W of an overlapping region was 20 μm. Theformed light-emitting unit was covered by a sealing film, and then asealing member having a barrier film formed thereon was fixed to thelight-emitting unit with an adhesive.

Comparative Example

Except that a glass plate having a refractive index of 1.5 and thethickness of 700 μm was used as a substrate, a light-emitting device wasmanufactured the same as the Example.

FIG. 13 is a chart which shows a result of measurement of a relationshipbetween observation angles and intensities of light leaked to the rearsurface in the light-emitting device according to the Example andComparative Example. In the chart, the observation angle when viewingthe rear surface side directly from a direction perpendicular to thesubstrate is set to 0 degrees, and an inclination angle from thatdirection is shown as the observation angle. Meanwhile, formeasurements, the intensity of light-emission on the front surface sidewas set the same in the Example and the Comparative Example.

According to the result shown by the chart, a decrease in leakage ofintensity of light from the rear surface was observed more in Examplethan Comparative Example at all observation angles.

The embodiment and the examples are described above referring to thedrawings, but these are examples of the present invention and variousconfigurations other than those described above can be employed.

The invention claimed is:
 1. A light-emitting device comprising: alight-transmitting substrate; a plurality of light-emitting units formedon the substrate, each light-emitting unit comprising alight-transmitting first electrode, a light-reflective second electrode,and an organic layer located between the first electrode and the secondelectrode; a light-transmitting region located between the plurality oflight-emitting units; and an insulating film that defines an end of thelight-emitting unit, wherein a sealing member is fixed to thelight-emitting unit directly or through an adhesive layer, and whereinwhen a thickness of the substrate is d and a width of a portion of thesecond electrode that is further on the outer side of the light-emittingunit than the end is W, d/2≤W is established.
 2. The light-emittingdevice according to claim 1, wherein the plurality of light-emittingunits extend in a same direction when viewed from a directionperpendicular to the substrate.
 3. The light-emitting device accordingto claim 1, wherein the thickness d of the substrate is equal to or lessthan 100 μm.
 4. The light-emitting device according to claim 1, whereinwhen a refractive index of the substrate is n,d×tan(arcsin(1/n))≤W<3d×tan (arcsin(1/n)) is satisfied.
 5. Thelight-emitting device according to claim 4, wherein2d×tan(arcsin(1/n))≤W<3d×tan(arcsin(1/n)) is satisfied.
 6. Thelight-emitting device according to claim 4, wherein the substratecomprises a plurality of layers, and the refractive index is arefractive index of the thickest layer of the plurality of layers. 7.The light-emitting device according to claim 4, wherein the substratecomprises a plurality of layers, and the refractive index is a meanvalue of refractive indexes of the plurality of layers.
 8. Thelight-emitting device according to claim 1, further comprising acovering film that directly covers the light-emitting unit, theinsulating film, and the substrate in the light-transmitting region. 9.A light-emitting system comprising: a light-transmitting partitionmember that partitions a space from an exterior; a light-transmittingsubstrate disposed on the partition member; a plurality oflight-emitting units formed on one surface of the substrate, eachlight-emitting unit comprising a light-transmitting first electrode, alight-reflective second electrode, and an organic layer located betweenthe first electrode and the second electrode; a light-transmittingregion located between the plurality of light-emitting units; aninsulating film that defines an end of the light-emitting unit; and acovering film that directly covers the light-emitting unit, theinsulating film, and the substrate in the light-transmitting region,wherein when a thickness of the substrate is d, and a width of a portionof the second electrode that is further on the outer side of thelight-emitting unit than the end is W, d/2≤W is established.